Ketamine is an FDA approved dissociative anesthetic agent that has been in clinical and/or investigational use for approx. 25 yrs, frequently in pediatric, aged or poor risk population. However, ketamine is notably associated with mild "emergence" reactions, characterized by altered preceptions, bizarre or impoverished thought content and impaired cognition. Ketamine emergence reactions have generated interest because they produce a mild and transient model of schizophrenia like symptoms and because of the recent discovery that ketamine is an NMDA receptor antagonist with important effects on neuronal function in a brain circuit implicated in schizophrenia. The recently articulated NMDA receptor hypofunction (NRH) hypothesis predicts that NMDA receptor antagonists can produce transient NRH with corresponding transient schizophrenic symptom manifestations.